Unblemished white teeth have long been considered cosmetically desirable. Unfortunately, in the absence of thorough dental cleaning, teeth can become discolored or stained from color-causing substances present in food, beverages, tobacco, and the like, and internal sources such as blood, amalgam-based fillings, and antibiotics (e.g., tetracycline).
Currently, there are a number of methods for removing stains in teeth. These methods are generally based on the use of abrasives, hydrolytic agents or oxidizing agents to break down the staining material. For example, mechanical methods of tooth cleaning are known whereby the stain is mechanically abraded through the use of abrasives or polishing agents normally employed in toothpaste preparations. Typical preparations containing abrasives are toothpastes, gels or powder dentifrices, which require close contact with the teeth. Brushing and similar scrubbing or polishing action is typically required as a compliment to successful stain removal. Typical abrasives include hydrated silica, calcium carbonate, sodium bicarbonate and alumina.
Hydrolytic agents including proteolytic enzymes can also be used to whiten teeth. These products are usually in the form of pastes or gels, and function to whiten teeth by removing the plaque and calculus that have entrapped the stain.
Oxidizing agents such as urea peroxide, hydrogen peroxide or calcium peroxide, represent the most common forms of whitening agents for tooth enamels. It is believed that peroxides whiten teeth by releasing hydroxyl radicals capable of breaking down the plaque/stain complex into a form that can be flushed away or removed by an abrasive.
Other active stain-removing components include surface-active agents, such as anionic surfactants and chelators, which have been incorporated into stain-removing compositions because of their stain-removing properties. For example, anionic surfactants typically employed in dentifrice compositions include sodium lauryl sulfate and sodium N-lauryl sarcosinate. Furthermore, chelators, such as polyphosphates, are typically employed in dentifrice compositions as tartar control ingredients. For example, tetrasodium pyrophosphate and sodium tri-polyphosphate are typical ingredients found in such compositions.
Stain-removing gum compositions are known. For example, gum compositions including sodium tripolyphosphate and xylitol are known. Also, gum compositions are known, which include hexametaphosphate and an abrasive silica material. Moreover, a dental gum is known, which includes the following ingredients: sodium tripolyphosphate, tetrasodium pyrophosphate, a silica abrasive and zinc acetate. A whitening gum composition is also known, which includes the abrasives sodium bicarbonate and calcium carbonate, and is sold under the brand name V6®.
Moreover, stain-removing gum compositions are known that include anionic surfactants such as fatty acid salts. For example, sodium stearate is a fatty acid salt employed in a gum product sold under the brand name Trident White® (see U.S. Pat. Nos. 6,471,945, 6,479,071 and 6,696,044). Furthermore, copending, commonly-owned U.S. patent application Ser. No. 10/901,511 discloses stain-removing gum compositions containing a salt of ricinoleic acid.
Unlike toothpaste, mouthwash and other dentifrice compositions, tooth whitening gum compositions present unique problems. For example, certain tooth whitening active ingredients can react adversely with other ingredients in gums. This results in short shelf-life, as well as the production of undesirable by-products. For example, certain anionic surfactants interact with lecithin, which is often used in gums and other food products to help different parts mix together well. Moreover, phosphate salts, such as polyphosphates, and certain anionic surfactants undergo changes in acidic formulations, such as fruit gums.
In view of the foregoing, it would be beneficial to provide further gum compositions for cleaning teeth. In particular, it would be beneficial to provide a tooth whitening gum where the stain-removing active agent was encapsulated within a barrier coating that substantially prevents the active agent from reacting with other gum ingredients.